Recent cell phones adopt CDMA (code division multiple access) method. However, as shown FIG. 4, communication of the cell phone is, in some cases, affected by a location or an environment when the cell phone 1 captures a base station 2. A receiving (downward) signal 3 from the base station 2 to the cell phone 1 is received by the cell phone 1, while a transmitting (upward) signal 4 is not received by the base station 2. Provided that the cell phone 1 transmits a request for location registry to the base station 2 under the state shown in FIG. 4, the base station 2 cannot receive the request. This leads to continuing of transmitting of the request by the cell phone 1, resulting in not only interfering with communications of other cell phones but also reducing a success rate in the communications in the total system.
On the other hand, the request continuation leads to increase of power consumption of the cell phone 1 which is typically battery driven and to running down of the battery.
In JP-P2001-128226A, when the location registry fails, ceasing operations of transmitting and receiving for a preset period prevents the power consumption from increasing. After the preset period, the cell phone 1 may succeed in the location registry with recovery of radio wave condition. However, the location registry must be stopped until the preset period is elapsed so that this approach seems to be of less practical use.